The present invention relates generally to floating platforms on a body of water or other liquid. More particularly, the present invention relates to water-borne crafts which can form a long, continuous surface such as a runway capable of handling the takeoff and landing requirements of large fixed-wing aircraft.
Military and civilian aircraft operations in the world today often require landing facilities in areas remote and distant from land-based airfields, particularly in flights conducted over large bodies of water. Although military ships like aircraft carriers serve in some extent to fill these needs, these monolithic hulled ships are typically only 1000 feet in length and only capable of servicing the landing requirements of smaller single seat or multi-seat airplanes. Larger cargo aircraft such as the C-17 or the smaller C-130 would likely require runways on the order of about 5000 feet, and ships capable of servicing such aircraft do not currently exist.
The theoretical solution of building a large floating platform for landing airplanes like transport aircraft faces practical difficulties related to deploying such a large structure at sea. Wave and weather conditions, in sea states where these platforms would be needed, place enormous stress on the structural integrity of such a platform. The lack of such a floating platform in the world today can be attributed in part to the technical challenges presented by the inclimate conditions encountered at sea.
Earlier attempts to design a suitable ocean-going platform proposed a conventional monolithic floating structure. In these cases, tests revealed that the vertical plane bending moment caused by waves was beyond the limits of the rigidly formed monolithic hull. The monolithic hull was too long to handle tumultuous wave conditions. Its transverse bending and torsional resonant periods in the zone of wave periods and its wave induced bending and torsional moments were not acceptable.
Other prior designs attempted to address this problem by de-coupling the modules in one degree of freedom, such as using hinges between modules to decouple the pitch degree of freedom. However, none of the remaining five degrees of freedom at the module interfaces were de-coupled. These designs were technically infeasible due to excessive transverse bending and torsional loads, and a transverse bending resonant period in the region of the exciting wave periods. While there is merit in the concept for pitch-axis stability, the concept was unsatisfactory as it lacks structural integrity in both transverse bending and torsion (i.e. yaw and roll). Sea states within which the platform operates would likely produce waves that would destroy such a structure.
Further design concepts proposed the use of universal joints to eliminate the large moments and resonant periods. However, the shear loads in the connectors are excessive, 10 to 100 times larger than typical in the design of floating oil field equipment. Structural elements capable of resisting the huge loads would be impractical to build. As mechanical loads under design wave conditions are far too great for connections between the modules can withstand, a practical concept for an inter-module connector that fixedly attaches modules that could mechanically stabilize the structure in all three axes is infeasible.
Accordingly, it is desired to design a floating platform capable of withstanding torsion and transverse bending loads/resonant dynamics encountered in unstable, high seas. It would further be desirable if the floating platform were included a runway capable of handling the operational takeoff and landing needs of large, fixed-wing cargo aircraft.